| Merthyr Tudful to Mitchell (South Dakota) | 4,115.90 mi (6,623.90 km) |
| Merthyr Tudful to Mitchellville (Maryland) | 3,516.28 mi (5,658.90 km) |
| Merthyr Tudful to Moberly (Missouri) | 4,115.97 mi (6,624.02 km) |
| Merthyr Tudful to Mobile (Alabama) | 4,372.90 mi (7,037.50 km) |
| Merthyr Tudful to Modesto (California) | 5,209.26 mi (8,383.49 km) |
| Merthyr Tudful to Mokena (Illinois) | 3,841.06 mi (6,181.59 km) |
| Merthyr Tudful to Moline (Illinois) | 3,943.75 mi (6,346.85 km) |
| Merthyr Tudful to Moncks Corner (South Carolina) | 3,915.42 mi (6,301.26 km) |
| Merthyr Tudful to Monfort Heights (Ohio) | 3,820.81 mi (6,149.00 km) |
| Merthyr Tudful to Monmouth (Oregon) | 4,864.78 mi (7,829.11 km) |
| Merthyr Tudful to Monroe (Georgia) | 4,038.83 mi (6,499.86 km) |
| Merthyr Tudful to Monroe (Louisiana) | 4,441.31 mi (7,147.60 km) |
| Merthyr Tudful to Monroe (Michigan) | 3,648.50 mi (5,871.70 km) |
| Merthyr Tudful to Monroe (North Carolina) | 3,851.07 mi (6,197.70 km) |
| Merthyr Tudful to Monroe (Ohio) | 3,799.06 mi (6,114.00 km) |
